Set screw and two piece clamshell type leak and dimpling barrels...not a good idea. I like the clamp style, but due to irregularities, wall thickness and such, there is still the possibility for leakage. We sat back and said..."How can we make a more reliable, no leak gas block?" Well, we figured it out and those that have used it have told us it is the best they have used. We use them on all of our upper builds.